So, let me clarify a few points.
1. You were mugging with a guy named Carlos "Lil Peanut" Blanco, however you were both using alt chars. Why don't you mug people on your actual main characters? Throwing a little time into an alt char so you can mug people doesn't mean it's not a mugging character. It's just that you've been banned for mugging characters in the past and have thought yourself as finding a way around the rule. Mug on your actual characters that you're scared to lose.
2. You've been pked 6+ times in the past few months, most of those characters also being named "Spintavion" and mugging people and getting in shootouts with police.
3. You and your buddy, both from De Leon used alt chars to fund his main de leon char. You did not use your de leon char because you're scared of getting pked. You chose to use your spintavion character because it's less risk and you've put less effort into it.
4. The proof is literally in you, taking someone who you're mugging with on alt chars, and putting their main de leon char as having access to the ATM to which you store stolen items.
5. Point blank, it's staff discretion here. Obviously you were acting as a middle man and assisting in this item transfer, obviously you have a history which indicates it wasn't some oopsie daisy mistake, and you were banned and pked for it. Next time, mug on your de leon character, or one of your other actual faction characters that you're scared to lose. You put other peoples main characters at risk when you mug them, and the playing field isn't even the way you're doing it.